Screenwriter "Esther Dale" is a pseudonym for Elaine May. May did not want her real name to be credited when she wasn't directing. So, for this reason alone, she decided to use this pseudonym. She was rather annoyed with director Otto Preminger for revealing her identity when promoting the film, although he praised her work.
The original novel by Lois Gould was much more serious in tone; many of the barbed, humorous lines of the film are missing entirely from the book. Otto Preminger saw the satirical potential in such a premise and had it written as such.
When Ken Howard shows Dyan Cannon the nude photo he took of her, the face is Cannon's but the body is someone else's. Dyan Cannon was uncomfortable doing a nude scene, especially directed by Otto Preminger, so she went for this option.
Novelist-screenwriter Joan Didion is said to have contributed to the screenplay (credited to Esther Dale, or rather Elaine May). Her work is uncredited.
Preminger was signed to a seven-picture deal with Paramount, perhaps the most lucrative director/studio contract up to that time. The deal fizzled directly after this movie's release, the fourth picture in that deal.